Bellew was the underdog after making the step up from cruiserweight, but the WBC champion dropped an injured Haye - who ruptured his Achilles tendon - twice before the fight was halted in the 11th round.
The Liverpudlian has been linked with a number of high-profile bouts later in the year, including the rematch against Haye, but Coldwell has suggested that Bellew should either call time on his professional career or face WBO heavyweight champion Joseph Parker.
Coldwell told Sky Sports News: "I understand why Tony would want to carry on, because the world is his oyster now. Imagine fighting for a world heavyweight title, that's massive.
"If he was going to fight again, for me, it would be Joseph Parker, who is about 6'4" tall, he's not a giant. He's a very good fighter, but he's not the best of the champions. If Tony was going to fight again, then maybe Parker for me.
"Genuinely, I want Tony to retire now. The dream was him to become world champion. Mission accomplished, as far as I'm concerned, this was a bonus. Now we have won, I genuinely want him to walk off into the sunset."
Haye has said that he is willing to travel to Merseyside should Bellew grant him a second showdown at the end of the year.